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Sharp MZ-800 Service Manual page 7

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4-1. Memory map
The MZ-800 has a different memory map depending on
o
MZ-800 memory map
FFFF"
EOOO
0000
COOO
AOOO
01000
- -
4000
2000
1000
MAIN
o-RAM
64K.
O-RAM
MZ-700 mode
r---,
~
~
ROM
~
~
VRAM
MZ-800 mode
MAIN
o-RAM
64 KB
O-RAM
MZ-800
the mode. To have compatibility with the MZ-700, it has
two modes of the MZ-700 mode and MZ-800 mode.
O
[J
D
OVOR"' ; : __ ,
I
I
I
I
:
:
I n :
lml:
~
__ J
L __
J
,.--,
1
I
1
I
: IIV) I
1
I
1
I
L __
oJ
~
640 )( 200
mode
VRAM
320 x 200 mode
NOTE:
r--..,
1
1
: eX):
1
1
,- __ .J
Item within dotted lin.
represents an option unit
MZ·1R25
Memory map changes after initial program loading
$0000
SI 000
$2000
$8000
SEooo
SFFFF
®
Power on (resel)
MZ-800 mode
MON. ROM
CG.ROM
DRAM
V-RAM
(320x2oo mode)
DRAM
MON. ROM
@
At start of monitor
MZ-700 mode
$0000
r - - - - - - ,
MON. ROM
$1000
r-----;
LD A, 08H
OUT (CE), A
=>
DRAM
SDOOO
V-RAM
SEooo
SE010
I<.!'Y.
nM~K
MON. ROM
SFFFF
• Memory map at power on is in the MZ-800 mode as
in
®,
but it changes to the MZ-700 mode by the
monitor ROM when the monitor program starts. After
transferring the CG data to the VRAM PCG area from
the CG ROM at
@,
the memory map then returns to
®.
• When the system program is completed to load, the
memory map goes into the MZ-700 mode if the
system switch (SW1) is set to ON side. If set to OFF
side, it changes to the MZ-800 mode, then the
memory map as in
@.
During those changes, all
memory spaces are composed of RAM and isolated
from ROM and VRAM.
IN (EOH), A
=>
©
Wril. 10 PeG from CG
MZ-7oo mode
$0000
$1000
$2000
MON. ROM
CG.ROM
D-RAM
@
System operation
MZ-7oo & 800 modes
$0000
D-RAM
IN (El H), A
~
6
SCOOO
V-RAM (CG)
SDOOO
SEooo
V-RAM
SE010
MON. ROM
SFFFF
SFFFF
L... _ _ _ ---'
• Depression of the manual reset switch assumes
memory map transition in order of
®
~
®
~
@
~
®,
similar as in the case of power on.
• However, depression of the reset switch in conjunc-
tion with the
I
CTRL
I
key assumes the memory map of
@ after being changed once to the MZ-700 or MZ-800
mode depending on the state of the system switch. In
the case of the MZ-800 mode, it is set to the plane
I.
IT (4-color mode) of the 320 x 200 mode.

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